This invention relates to a method of operating a reactor and, more particularly, to a method for improving the reaction efficiency of a fluidized bed reactor.
The use of fluidized bed reactors, in the form of combustors, gasifiers or steam generators has been recognized as an attractive means of generating heat. In the operation of these reactors air is passed through a bed of particulate material which includes a mixture of inert material, a fuel material such as high sulfur, bituminous coal and, usually, an adsorbent material, such as limestone, for the sulfur formed as a result of the combustion of the coal. As a result of the air passing through the bed the bed is fluidized which promotes the combustion of the fuel. The basic advantages of such an arrangement are many and include a relatively high heat transfer rate, a substantially uniform bed temperature, combustion at relatively low temperatures, ease of handling the fuel materials, a reduction in corrosion and boiler fouling and a reduction in boiler size.
However, in these type of methods, the limestone is in a less than optimum condition with respect to surface hardness, sulfur adsorption properties and catalytic properties.
For example, during initial operation of the bed and especially when the coal being utilized has a low sulfur content, the limestone remains soft and tends to degrade before it has a chance to react with the sulfur and form an outer, relatively hard shell. This increases the amount of limestone needed to be fed to the system to maintain the required bed depth. This premature degradation also decreases the adsorption and catalytic properties of the limestone.